In the field of steroids 17.alpha.-hydroxy-20-oxopregnane derivatives are utilized as intermediates in the syntheses of the glucocorticoidal hydrocortisone hormone and antiinflammatory corticosteroid drugs (prednisolone, triamcinolone, dexamethasone, betamethasone and the like) developed therefrom, as well as the gestagenic 17.alpha.-hydroxyprogesterone-17-ester derivatives (17.alpha.-hydroxyprogesterone capronate, chlormadinone acetate and the like) and the antiandrogenic drug cyproterone acetate.
The 17.alpha.-hydroxy-20-oxopregnane derivatives used as intermediates in the pharmaceutical industry are prepared on the one hand by transforming 3.beta.-acetoxy-5,16-pregnadien-20-one obtained from the chemical decomposition of diosgenin and of the structurally related solasodine, a steroidal alkaloid [N. Applezweig: Steroid Drugs Vol. 1., page 56, McGraw Hill Corporation, New York, 1962]; and on the other hand, by the synthetic building up of the pregnane side chanin from 17-oxo steroids containing the androstane skeleton [J. Fried and J. A. Edwards: Organic Reactions in Steroid Chemistry, Vol. 2, page 127, van Nostrand Reinhold Company, N.Y., 1972].
It is known that 17(20)-dehydro-23,24-dinorcholanoic acid [U.S. Pat. specification No. 4,132,408], 9.alpha.-hydroxy-3-oxo-23,24-dinor-4,17(20)-choladien -22-oic acid [M. G. Wovcha et al.: Biochim. Biophys Acta 531, 308 (1978); published European patent application No. 0,011,235; A. Jekkel et al.: J. Gen. Microbiol. 135, 1727 (1989)] and 3.beta.-hydroxy-23,24-dinor-5,17(20) -choladien-22-oic acid [Hungarian patent specification No. 190,665 (1980)] can be prepared by the partial microbiological decomposition of the side chain of natural sterols.
Natural sterols, particularly those of plant origin, such as the mixture of .beta.-sitosterol and campesterin obtained from soy bean or sterol mixtures obtaned from the side products of wood processing are available in large quantities.